ltc3827ig-1 Linear Technology Corporation, ltc3827ig-1 Datasheet
ltc3827ig-1
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ltc3827ig-1 Summary of contents
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FEATURES Wide Output Voltage Range: 0.8V ≤ V ■ ■ Low Operating I : 80μA (One Channel On) Q ■ Out-of-Phase Controllers Reduce Required Input Capacitance and Power Supply Induced Noise ® ■ OPTI-LOOP Compensation Minimizes C ±1% Output Voltage ...
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... TAPE AND REEL LTC3827EG-1 LTC3827EG-1#TR LTC3827IG-1 LTC3827IG-1#TR Consult LTC Marketing for parts specified with wider operating temperature ranges. Consult LTC for information on nonstandard lead based finish parts. For more information on lead free part marking, go to: For more information on tape and reel specifications, go to: ...
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ELECTRICAL CHARACTERISTICS temperature range, otherwise specifications are at T SYMBOL PARAMETER I Input DC Supply Current Q Sleep Mode (Channel 1 On) Sleep Mode (Channel 2 On) Shutdown Sleep Mode (Both Channels) UVLO Undervoltage Lockout V Feedback Overvoltage Lockout OVL ...
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LTC3827-1 ELECTRICAL CHARACTERISTICS Note 1: Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. Exposure to any Absolute Maximum Rating condition for extended periods may affect device reliability and lifetime. Note 2: The LTC3827E-1 ...
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W U TYPICAL PERFOR A CE CHARACTERISTICS Inductor Current at Light Load FORCED CONTINUOUS MODE 2A/DIV BURST MODE PULSE SKIPPING MODE 4μs/DIV FIGURE 13 CIRCUIT V = 3.3V OUT I = 300μA LOAD Total Input Supply Current vs Input Voltage ...
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LTC3827 TYPICAL PERFOR A CE CHARACTERISTICS Foldback Current Limit 120 TRACK/ 100 0.6 0.7 0.8 0 0.1 0.2 0.3 0.4 0.5 0.9 FEEDBACK VOLTAGE (V) 38271 G16 TRACK/SS Pull-Up Current vs ...
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W U TYPICAL PERFOR A CE CHARACTERISTICS Undervoltage Lockout Threshold vs Temperature 4.2 4.1 4.0 3.9 RISING 3.8 3.7 3.6 3.5 FALLING 3.4 3.3 3.2 15 –45 –30 – TEMPERATURE (°C) 38271 G25 U U ...
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LTC3827 CTIO S BG1, BG2 (Pins 23, 18): High Current Gate Drives for Bottom (Synchronous) N-Channel MOSFETs. Voltage swing at these pins is from ground to INTV BOOST1, BOOST2 (Pins 24, 17): Bootstrapped Supplies to ...
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U OPERATIO (Refer to Functional Diagram) Main Control Loop The LTC3827-1 uses a constant frequency, current mode step-down architecture with the two controller channels operating 180 degrees out of phase. During normal opera- tion, each external top MOSFET is turned ...
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LTC3827-1 U OPERATIO (Refer to Functional Diagram) Light Load Current Operation (Burst Mode Operation, Pulse-Skipping, or Continuous Conduction) (PLLIN/MODE Pin) The LTC3827-1 can be enabled to enter high efficiency Burst Mode operation, constant frequency pulse-skipping mode, or forced continuous conduction ...
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U OPERATIO (Refer to Functional Diagram) Frequency Selection and Phase-Locked Loop (PLLLPF and PLLIN/MODE Pins) The selection of switching frequency is a tradeoff between efficiency and component size. Low frequency operation increases efficiency by reducing MOSFET switching losses, but requires ...
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LTC3827-1 U OPERATIO (Refer to Functional Diagram 2.53A IN(MEAS) (a) Figure 1. Input Waveforms Comparing Single-Phase (a) and 2-Phase (b) Operation for Dual Switching Regulators Converting 12V to 5V and 3. Each. The Reduced Input Ripple ...
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U U APPLICATIO S I FOR ATIO R Selection For Output Current SENSE R is chosen based on the required output current. SENSE The current comparator has a maximum threshold of 100mV/R and an input common mode range of SENSE ...
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LTC3827 APPLICATIO S I FOR ATIO core material saturates “hard,” which means that induc- tance collapses abruptly when the peak design current is exceeded. This results in an abrupt increase in inductor ripple current and consequent output voltage ...
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U U APPLICATIO S I FOR ATIO C and C Selection IN OUT The selection simplified by the 2-phase architec- IN ture and its impact on the worst-case RMS current drawn through the input network (battery/fuse/capacitor). It ...
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LTC3827 APPLICATIO S I FOR ATIO Setting Output Voltage The LTC3827-1 output voltages are each set by an external feedback resistor divider carefully placed across the out- put, as shown in Figure 3. The regulated output voltage is ...
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U U APPLICATIO S I FOR ATIO Alternatively, the TRACK/SS pin can be used to track two (or more) supplies during start-up, as shown qualitatively in Figures 6a and 6b this, a resistor divider should be connected from ...
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LTC3827 APPLICATIO S I FOR ATIO INTV current is limited to less than 24mA from a 24V sup- CC ply when in the G package and not using the EXTV T = 70°C + (24mA)(24V)(95°C/W) = 125°C J ...
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U U APPLICATIO S I FOR ATIO the input supply BOOST IN INTVCC boost capacitor C needs to be 100 times that of the total B input capacitance of the topside MOSFET(s). The reverse breakdown ...
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LTC3827 APPLICATIO S I FOR ATIO 900 800 700 600 500 400 300 200 100 0 0 0.5 1 1.5 PLLLPF PIN VOLTAGE (V) Figure 9. Relationship Between Oscillator Frequency and Voltage at the PLLLPF Pin When Synchronizing ...
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U U APPLICATIO S I FOR ATIO Efficiency Considerations The percent efficiency of a switching regulator is equal to the output power divided by the input power times 100 often useful to analyze individual losses to determine what ...
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LTC3827 APPLICATIO S I FOR ATIO Checking Transient Response The regulator loop response can be checked by looking at the load current transient response. Switching regulators take several cycles to respond to a step in DC (resistive) load ...
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U U APPLICATIO S I FOR ATIO Design Example As a design example for one channel, assume V 12V(nominal 22V(max OUT and f = 250kHz. The inductance value is chosen first based on a 30% ripple ...
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LTC3827 APPLICATIO S I FOR ATIO PC Board Layout Checklist When laying out the printed circuit board, the following checklist should be used to ensure proper operation of the IC. These items are also illustrated graphically in the ...
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U U APPLICATIO S I FOR ATIO not be along the high current input feeds from the input capacitor(s). – Are the SENSE and SENSE leads routed together with minimum PC trace spacing? The filter capacitor + – ...
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LTC3827 APPLICATIO S I FOR ATIO PC Board Layout Debugging Start with one controller time helpful to use a DC-50MHz current probe to monitor the current in the inductor while testing the circuit. ...
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U TYPICAL APPLICATIO CSS1 0.01μF C ITH1A 39pF 100pF C RB1 ITH1 R ITH1 1200pF 215k 10k I TH1 RA1 68.1k V FB1 SENSE1 C1 SENSE1 1nF PLLLPF PLLIN/MODE SGND RUN1 RUN2 C2 SENSE2 1nF SENSE2 RA2 22.1k V FB2 ...
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LTC3827-1 U TYPICAL APPLICATIO CSS1 0.01μF C ITH1A 100P C RB1 ITH1 R ITH1 470pF 365k 10k I RA1 69.8k V SENSE1 C1 SENSE1 1nF PLLLPF PLLIN/MODE SGND RUN1 RUN2 C2 SENSE2 1nF SENSE2 RA2 39. ITH2 R ...
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U TYPICAL APPLICATIO High Efficiency Synchronizable Dual 5V/8V Step-Down Converter CSS1 0.01μF C ITH1A 39pF 100pF C RB1 ITH1 R 470pF ITH1 365k 10k I TH1 RA1 69.8k V FB1 SENSE1 C1 SENSE1 1nF 10nF 10k PLLLPF PLLIN/MODE SGND RUN1 ...
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LTC3827-1 U TYPICAL APPLICATIO CSS1 0.01μF C ITH1A 47pF 220pF C RB1 ITH1 R ITH1 2.2nF 100k 7k I TH1 RA1 402k V FB1 SENSE1 C1 SENSE1 1nF PLLLPF PLLIN/MODE SGND RUN1 RUN2 C2 SENSE2 1nF SENSE2 RA2 402k V ...
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... FLASH SHALL NOT EXCEED .254mm (.010") PER SIDE Information furnished by Linear Technology Corporation is believed to be accurate and reliable. However, no responsibility is assumed for its use. Linear Technology Corporation makes no represen- tation that the interconnection of its circuits as described herein will not infringe on existing patent rights. ...
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... PolyPhase LTC3731 3- to 12-Phase Step-Down Synchronous Controller LTC3835/LTC3835-1 Low I Synchronous Step-Down Controller Q PolyPhase is a registered trademark of Linear Technology Corporation Linear Technology Corporation 32 1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408) 432-1900 FAX: (408) 434-0507 ● High Efficiency Dual 3.3V/8.0V Step-Down Converter ...